The preparation of L-.alpha.-glycerylphosphoryl-D-myoinositol (GPI) and the pharmaceutically acceptable salts thereof has not been described up to now.
Brown (J. Chem. Soc., 3774, 1959) and Brokeroff (J. Am. Chem. Soc., 2591, 1959) obtained L-.alpha.-glycerylphosphoryl-D-myoinositol as the cyclohexylammonium salt by acylating pure phosphatidylinositol (PI), a substance which is not commercially available and is obtained by means of a laborious process which cannot be carried out industrially.
Lapage (J. Am. Chem. Soc., 3713, 1960) obtained L-.alpha.-glycerylphosphoryl-D-myoinositol as the cyclohexylammonium salt by acylating maize crude phosphatides but, even though the purification is carried out on strong basic ion exchange resins with gradient elutions, the resulting cyclohexylammonium salt is not pure and repeated crystallizations must be performed in order to purify it.
The difficulty in obtaining pure L-.alpha.-glycerylphosphoryl-D-myoinositol starting from impure phosphatidylinositol (PI) was confirmed by Hawthorne (Biochem. J., 195, 1959), who isolated L-.alpha.-glycerylphosphoryl-D-myoinositol as the barium salt and obtained interesting results only by means of chromatography on strong basic ion exchange resins, with a gradient of a mixture of ammonium formate and sodium tetraborate and using pure phosphatidylinositol.